One technique for recording and playing back digital data is a data recording technique using, for example, an optical disk (including a magneto-optical disk), such as a CD (Compact Disk), an MD (Mini-Disk), or a DVD (Digital Versatile Disk), as a recording medium. Optical disk is a general term for recording media of the type in which a disc of a thin metal plate protectively coated with plastic is irradiated with laser light and a change in the reflected light is used to capture a signal.
Optical disks include, for example, playback-only disks known as CD, CD-ROM, DVD-ROM, and so forth, and user-data-recordable disks known as MD, CD-R, CD-RW, DVD-R, DVD-RW, DVD+RW, DVD-RAM, and so forth. The recordable disks employ the magneto-optical recording method, the phase-change recording method, the dye-change recording method, and so on to record data. The dye-change recording method is also referred to as a write-once recording method, which provides one-time-data-recordable and non-rewritable media. This is suitable for data preservation purposes and the like. On the other hand, the magneto-optical recording method and the phase-change recording method, which enable data to be rewritten, are employed for various applications, such as recording of various types of content data including music, motion pictures, games, and application programs.
Recently, high-density optical disks, referred to as DVR (Data & Video Recording), have been developed to achieve remarkably large capacity disks.
For example, in recently developed high-density disks, data recording and playback is conducted under the conditions wherein a laser (so-called blue laser) having a wavelength of 405 nm is combined with an objective lens having an NA (numerical aperture) of 0.85. In this case, about 23.3 GB (gigabytes) of data can be recorded and played back on a 12-cm-diameter disk with a format efficiency of about 82% at a track pitch of 0.32 μm and a linear density of 0.12 μm/bit in recording and playback units of 64-KB (kilobyte) data blocks.
High-density write-once or rewritable disks have also been developed.
In order to record data onto a recordable disk that employs the magneto-optical recording method, the dye-change recording method, the phase-change recording method, or the like, tracking guide means for a data track is required. Thus, a pregrooved disk, or a disk having grooves formed in advance, is used, and the grooves or lands (plateau portions in cross section between the grooves) are used as data tracks.
Furthermore, address information must be recorded in order to record data in position on a data track. In some cases, the address information is recorded using wobbled grooves.
Specifically, the track onto which data is to be recorded is formed in advance as, for example, a pregroove, and the sidewall of the pregroove is wobbled according to address information.
During recording or playback, the address is read from the wobble information that is obtained as reflected-light information. Thus, data can be recorded and played back in a desired position, for example, even when pit data or the like that indicates an address is not formed in advance on a track.
The address information added as wobbled grooves prevents the need for, for example, discrete address areas on the tracks to record addresses as, for example, pit data. The address areas are no longer necessary, and therefore, the recording capacity of live data becomes large.
The absolute-time (address) information expressed by the wobbled grooves is referred to ATIP (Absolute Time In Pregroove) or ADIP (Adress In Pregroove).
One known technique for such data-recordable (not playback-only) recording media is that a spare area is provided for replacing the area in which data is recorded on the disk. This is a defective-area management technique for performing appropriate recording and playback operations using a spare recording area in place of a portion unsuitable for data recording due to a defect on a disk, such as a scratch.
One defective-area managing technique is disclosed in, for example, PCT Japanese Translation Patent Publication No. 2002-521786.
In one-time recordable optical recording media, such as a CD-R, a DVD-R, and a high-density write-once disk, it is impossible to record data onto a recorded area.
Most file systems to be recorded onto optical recording media are specified on the assumption that the file systems are used on non-recordable playback-only media (ROM-type disks) or rewritable media (RAM-type disks). The file systems for one-time recordable media, i.e., write-once recording media, are specified so that certain functions are limited while special functions are added.
This is the reason that the file systems for write-once optical recording media are not widely popular. For example, FAT (File Allocation Table) file systems compatible with various types of OS in information processing devices cannot be immediately used for the write-once media.
Write-once media are suitable for data preservation and the like and are widely used. If write-once media is also capable of supporting the FAT file systems described above without changing the general specification thereof, write-once media would provide higher usability.
However, in order to immediately use widely accepted file systems, such as FAT file systems, or the RAM or hard-disk file systems, the capability of writing data at the same address, i.e., data rewritability, is essential. As is known, one of the features of the write-once media is non-rewritability, and it is therefore impossible to immediately use the file systems described above that are used for rewritable recording media.